Đề thi học kỳ 2 môn Tiếng Anh lớp 9 Phòng GD-ĐT Tam Đảo, Vĩnh Phúc năm học 2015 - 2016

Wood fuel is wood used as fuel. The burning of wood is currently the largest use of energy derived from a solid fuel biomass. Wood fuel can be used for cooking and heating, and occasionally for fueling steam engines and steam turbines that generate electricity. Wood fuel may be available as firewood (e.g. logs, bolts, and blocks), charcoal, chips sheets, pellets and sawdust. The particular form used depends upon factors such as source, quantity, quality and application. Sawmill waste and construction industry by- products also include various forms of lumber tailings. Wood may be burned in a furnace, stove, fireplace, or in a campfire, or used for a bonfire. Wood is the most easily available form of fuel, requiring no tools in the case of picking up dead wood, or little tools, although as in any industry, specialized tools, although as in any industry, specialized tools, such as skidders and hydraulic wood splitters, have evolved to mechanize production. The discovery of how to make fire for the purpose of burning wood is regarded as one of humanity's most important advances.